Fee and Commission Income - Additional Information (Detail) - EUR (€) € in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fee and commission income (expense) [abstract]
Fee and commission income on trust and fiduciary activities	€ 215	€ 190	€ 55

The amount of fee income and expense (other than the amounts included when determining the effective interest rate) arising from trust and other fiduciary activities that result in the holding or investing of assets on behalf of individuals, trusts, retirement benefit plans and other institutions.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2018-01-01
-Paragraph 20
-Subparagraph c
-Clause ii
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_20_c_ii&doctype=Standard
-URIDate 2018-03-16

Name:	ifrs-full_FeeIncomeExpenseArisingFromTrustAndFiduciaryActivities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration